Current interrupting apparatus



y 1942- c. L. STROUP CURRENT INTERRUPTING. APPARA'IfUS Filed March 2,1940 T0 l/NE 22 I 22 I 2/ a cmrzeszsm Patented July 14, 1942 UNITEDSTATES PATENT- OFFICE T T T .-2,2s9,3s9 T CURRENT m'rannur'rmc APPARATUSCharles L. Stroup, Oak Park, m'. Application March 2, 1940,- Serial Nb.321,868 (Cl. i'zs-aoi i 13 Claims.

My invention relates generally to electrical apparatus and it hasparticular relation to cur-. rent interrupting apparatus such aslightning arre'sters, in which arc extinction is efiected by means of ablast resulting from the creation of the arc and acting to blow out orcut oil the arc.

An object of my invention is to provide for extinguishing an arc in 'anew and improved manner by directing across a'section of its created asa result of the arc.

Another object of my invention is to provide for extinguishing an are byplacing a pair of electrodes at the open ends of a restricted arcpassageway so that a blast created therein by an arc will extinguish theare at either or both of the open ends. I

Another object of my invention is to provide for extinguishing an are byplacing an electrode to the side of an arc passageway so that a blastcreated therein by an arc will cut ofi or blow out the arc where itchanges direction toward the electrode.

Still another object of my invention is to provide for extinguishing an'are between a pair of electrodes by causing the arc to make a sharpchange in direction from its main or general path, and cutting off theare where it changes direction by a blast moving in a directiongenerally parallel to the main path of the arc.

Another important object of my invention is to prevent the puncture orbursting of a lightning arrester housing due to heavy electric arcs, byplacing the electrodes of the arrester in from the sides of the housing.

Other objects of my invention will in part be obvious and in part appearhereinafter.

Accordingly, my invention is disclosed in the embodiment thereof shownin the accompanying drawing, and it comprises the features ofconstruction, combination of elements and arrangement of parts whichwill be exemplified in the construction hereinafter set forth, and thescope of the application of which will be indicated in the appendedclaims.

path a blast Figure 1 is a vertical sectionalview through a lightningarrester unit illustrating one w'orlring embodiment of my invention;

Figure 2 is a sectional view, taken on line 2-2 ofFi'gurehand j I Figure3 is a view takenon line 3+3 of Figure 1.

While I have chosen to disclose my invention 1 as employed in alightning arrester, it will be apparent that it may also be employed foruse in other types of current interrupter, such as fuses or circuitbreakers;

For a more completeunderstanding of the.

nature and scope of my invention, reference may be had to the followingdetailed description,

taken in conjunction drawing, in which with the accompanying Referringnow to Figures 1, 2 and 3 of the drawing, a lightningarrester unit isindicated generally at Ill, comprising a fiber-tube'or housing with afiber cylinder l2 fitting closely therein approximatelymidway betweenthe open ends. Preferably, the cylinder I2 is of such size that it maybe easily inserted into the tube II with substantially no 'playtherebetween. The narrow clearance between the cylinder l2 and theinside of the casing ll provides a. restricted arc passage l3, the widthof which is shown greatly exaggerated in the drawing for purposes ofillustration.

The lightning arrester l0 shown in the drawingrepresents an actualworking embodiment of my invention and is shown in approximately fullscale dimensions in Figures 1, 2 and 3. The tube or casing H is 10inches long with an outside diameter of 2 inches. The cylinder I2 is 1%inches in height and has a diameter of 11-} inches. The width of the arcpassageway I3, or the clearance between the cylinder l2 and inside ofthe casing I I, isapproximately 3.0 thousandths of an inch in theworking device shown. T

A pair of disc-shaped electrodes I may be provided on opposite sides ofthe fiber cylinder l2, having bosses l5 fitting into recesses in thefaces of the fiber cylinder II to maintainalignment. The electrodes llmay be machined down so as to leave shoulders l6 at the faces abuttingthe cylinder 12. A pair of inner metal sleeves I1 and a pair of outerfiber sleeves l8 fit over the machined, portion of the electrodes M andrest against the shoulders Hi. It is not essential to the operation ofthe lightning arrester III that the sleeves I8 be formed of fiber. Theends of the metal sleeves l1 and fiber sleeves l8 maybe closed by a pairof washers. IS. The fiber sleeves l8'are of somewhat less diameter thanthe inside the sleeves l8 are about 2%. inches long and have a diameterof 11-} inches. And the annular spaces 2 0 are about inch in radialwidth.

A pair of end plugs '2! may be screwed; into, the ends of the fiber tubeI I, having a plurality of apertures 22 for outlet or discharge blastgases from within the lightning arrester unit it]. In order to connectthe lightning arrester unit in electrical relationship between line andground, a pair of terminals 23 in the form of bolts may be screwedcentrally through the plugs 2| and into threaded recesses in theelectrodes 14, as shown. An air gap, such as a sphere gap or a horn gap,should be provided in the line connection, according {to standardpractice, in order to prevent subjecting the lightning arrester unit IIIto continuous line voltage, with resultant leakage current and to avoidthe voltage hazard of a live piece of equipment.

Several difierent insulation materials other than hard fiber may beused. for the casing H,

cylinder l2, and the sleeves l8. Any material which evolves arcextinguishing gases under the heat of an electric 'arc may-have thenecessary are extinguishing properties. Certain woods, vegetable fiber,impregnated paper, and chemical compounds give of! arc extinguishinggases. Wood, fiber, paper and the like yield gases by destructivedistillation. These gases probably comprise both water vapor and lowerhydrocarbons. Chemicals, such as boric acid, yield water vapor by havingwater of crystallization driven oil by the heat of the arc.

The operation of the lightning arrester unit- It may be explained asfollows: The height of the fiber cylinder. l2 and corresponding distancebetween the electrodes I 4 largely determines the discharge rating orcapacity of the lightning arrester unit it). When the voltage impressedon the lightning arrester unit It exceeds its discharge rating, an arcwill be established between the electrodes l4. Such an arc will beformed between opposite points of the peripheries of the shoulders l6through the narrow or restricted space between the fiber cylinder i2 andthe inside of the tube II. It will be noted that the main path of suchan arc is parallel with the axis of the tube H but that the arc mustturn in at each end to reach the opposing points on the shoulders I6.Having the shoulders It thus inset a. short way from the periphery ofthe faces of the cylinder I 2 serves to aid in the extinguishment of anarc. Gases will be driven oil from the cylinder 12 and tube H by the arcflowing therebetween to create a blast which moves with tremendousvelocity out the opposite ends of the narrrow space between the cylinderl2 and the inside of the tube H, into the relatively open annular spaces29. It will be seen that this blast moves in a direction generallynormal to the portions of the are which turn in to reach the shouldersl6. Such a transverse blast either cuts off the turned-in or normalportions of the are immediately at the edges of the cylinder H, orforces the arc in loop form up into the open annular spaces 20, Whereits extinguishment is aided by the gases evolved from the fiber sleevesl8 and the tube H. The end plugs 21 are spaced sufliciently far from theelectrodes I4 so that there is no possibility of the arc restriking orbeing extended therebetween, or, if necessary, the plugs 2| may be madeof insulating material.

An are established between opposing points on the shoulders IE will burnopposing groove or furrows into the fiber cylinder l2 and fiber tube II,as indicated at in Figure 2 of the drawing. The thickness of the grooves25 is greatly exaggerated in Figure 2 for purposes of illustration.

An arc will not usually be reestablished between the same pair ofopposing points on the shoulders 56 of the electrodes M.

A very important feature of my invention is in having the shoulders l6of the electrodes [4 spaced from the inside of the casing or tube ll, soas to leave expansion spaces therebetween. It has been found that onplacing electrodes against an arrester housing, heavy arcs will punctureand burst the housing. My improved lightning arrester is capable ofwithstanding a number of heavy current arc discharges without failure byreason of the housing being punctured or broken adjacent to theelectrodes.

Since certain changes can be made in the foregoing construction, anddifferent embodiments of the invention may be made without departingfrom the scope thereof, it is intended that all matters shown in theaccompanying dawing or described hereinbefore shall be interpreted asillustrative and not in a limiting sense.-

I claim as my invention:

1. In a circuit interrupting device, in combination, a fiber housing, animperforate fiber plug wall of said fiber plug and. the inside of saidfiber housing providing a restricted arc passageway open at the ends, apair of electrodes disposed at the opposite ends of said fiber plug,said electrodes being laterally spaced from the discharge path of gasesfrom said restricted arc passageway so that an are established betweensaid electrodes must make at least two changes in directiontherebetween, and said are established between said electrodes beingextinguished by a blast shooting out the open ends of said restrictedarc passageway and cutting off said are where it turns at the open endsof said restricted arc passageway to meet said laterally spacedelectrodes, said blast being created by gas evolution from said fiberhousing and said fiber plug defining said restricted arc passageway.

3. A lightning arrester comprising, in combination, a fiber tube, arelatively short fiber block fitting closely within said fiber tube andleaving a narrow space therebetween, a pair of electrodes disposedagainst the opposite ends of said fiber block, the peripheries of saidelectrodes lying within the peripheries of the opposite ends of saidfiber block, a pair of fiber sleeves extending outwardly from said pairof electrodes, the periphery of said fiber sleeves being substantiallyless than the internal periphery of said fiber tube so as to providerelatively wide annular spaces therebetween, means for closing the endsof said fiber tube having apertures therein for gas outlet, and terminalmeans individual to each of said electrodes.

4. A lightning arrester comprising, in combination, a fiber tube, arelatively short fiber block fitting closely within said fiber tube andleaving a narrow space therebetween, a pair of electrodes disposedagainst the oppositeends of said fiber block, the peripheries of saidelectrodes lying within the peripheries of the opposite ends of saidfiber block, a pair of fiber sleeves extending outwardly from said .pairof electrodes, the periphery of said fiber sleeves being substantiallyless than the internal peripheryof said fibertube so as to providerelatively wide annular spaces therebetween, means for closing the endsof said fiber tube having apertures therein for gas'outlet, and terminalmeans individual to each of said electrodes, said narrow space betweenthe inside of said fiber tube and the outside of said fiber blockforming a restrictedare passageway opening at its ends into ,said,relatively wide annular spaces formedby said fiber sleeves and the outerportions of said fiber tube. a

5. A lightning arrester comprising, in combination, a cylindrical fibertube, arelativelyv short fiber cylinder fitting closely within" saidcylindricalfiber tube'and substantially midway between the ends;thereof, a pair of? disc-shaped electrodes fitting against the endfaces of said 'short fibercylinden'thelaterah edges of said electrodeslying a shortudistance :in. from the peripheries of the endfaces ofsaidshort fiber cylinder, a pair of cylindrical fibersleeves fitting onsaid electrodes and'extending outwardly therefrom toward the ends ofsaid cylindrical fiber tube, said. cylindrical fiber sleeves beingsubstantially less 'in' diameter than the inside of said cylindricalfiber tube so as to "leaver relatively wide annular spaces therebetween;apair of plugs closing the outer ends of said cylindrical fiber tube andhaving a plurality of. apertures therein for blastdischarge, and a pairof terminal posts extendingoutwardly from said electrodes throughtheendsof said cylindrical fiber tube, the narrow space between theoutside of said short fiber cylinder and the inside of said cylindricalfiber tube providing a restricted arc passageway for an are establishedbetween said electrodes, the spacing of the lateral edges of saidelectrodes in from the peripheries of the end faces of said short fibercylinder causing such anarc at its outer ends to take pathssubstantially normal to the axis of said cylindrical fiber tube wherebya blast created in' said restricted arc passageway shoots out of, theopposite ends thereof into said relatively wide annular spaces in adirection parallel? to the axis of said cylindrical tube to cut off saidarc-at said sections of its path normal thereto. 6'. A circuitinterrupting device comprising, in

combination, a pair of electrodes in spaced end to end relation betweenwhich an arc may be formed, means providing a restricted .arcpassagewayv between said spaced electrodes in material adapted to evolvean arc extinguishing medium due to the heat of the arc, at least one endof said are pasageway being open and the electrode thereatbeing spacedlaterally from the discharge path of said medium out, of said'arcpassageway" whereby the are established between said electrodes isrequired to follow a path transverse to the path of said medium as it isdischarged from said open end and is extended and extinguished thereby,conductor means extending from the electrode at said open end of saidpassageway, and insulating means surrounding said conductor means for asubstantial distance from the electrode fromwhich' it extends. I

7. A circuit interrupting device comprising, in combination, a pair ofelectrodes in spaced end to vend'relation between which an arc may beformed, and means providing a restricted arc material adapted to evolvean arc extinguishing medium due to the heat of thearc, both ends ofsaidare passageway being open and the electrodes thereat being spacedlaterally from the discharge path of said medium out of said arepasageway whereby the 'arcestablished between said electrodes isrequired to follow paths transverse to the path of said medium as it'isdischarged from said open ends and is-extended and extinguished thereby.I

8. A circuit interrupting device comprising, in combination, a pair ofelectrodes in spaced end to end relation between which an arc may beformed, means providingfa restricted arc passageway between said spacedelectrodes in material adapted to evolve an arc extinguishing medium,due to the heat of the arc, both ends of said arc passageway being openand the electrodes thereat being spaced laterally'from the dischargepath of said medium out of said are passageway whereby the areestablished between said electrodes isreduired to follow pathstransverse to the path of said medium as it is discharged from saidopen' ends and is extended and extinguished thereby, conductor meansextending e'ndwise from each of said electrodes, and insulating meanssurrounding each conductor means for a substantial distance from theelectrode from which it extends.

and means providing a restricted arc passageway between said spacedelectrodes in material adapted to evolve an arc extinguishing medium dueto the heat of the arc, both ends of said arc passageway being open andthe electrodes thereat being spaced laterally from the discharge path ofsaid i medium out of said are passageway whereby the arc establishedbetween said electrodes is required to follow paths transverse to thepath of said medium as it is discharged from said open ends and isextended and extinguished thereby.

10. In a circuit interrupting device, in combination, a relatively longtubular housing, a relatively short imperforate plug fitting closelywithin said tubular housing intermediate its ends, said housing and plugbeing formed of insulating material capable of evolving an arcextinguishing medium due to the heat of an arc, electrodes at the endsof said imperforate plug between which an arc may be formed along thejuxtaposed surfaces of said housing and plug, a conductor rod extendingaxially from each electrode out of its end of said housing; and a sleeveof insulating material extending outwardly from each electrode andspaced from the inner surface of said housing to provide therebetween agas expansion space.

11. In a circuit interrupting device, in combination, a relatively longtubular housing, a relatively short imperforate plug fitting closelywithin said tubular housing intermediate its ends,-

said housing and plug being formed of insulating material capable ofevolving an arc extinguishing medium due to the heat of an arc,electrodes at the ends ofrsaid imperforate plug between which an arc maybe formed along the juxtaposed surfaces of said housing and plug, aconductor rod extending axially from each electrode out oi its end ofsaid housing, and a sleeve of insulating material extending outwardlyfrom each electrade and spaced from the inner surface of said housing toprovide therebetween a gas expansion space, thegas expansion space ateach end of said housing being vented to the atmosphere through aplurality of apertures.

12. In a lightning arrester, in combination a tubular housing, a plugwithin said tubular housing' spaced a substantial distance from at leastone end thereof, said housing and plug being formed of insulatingmaterial capable of evolving an arc extinguishing medium due to the heatof an arc, electrodes at the ends of said plug between which an arc maybe formed along the juxtaposed surfaces of said housing and plug, aconductor rod extending axially out of said one end of said housing fromthe adjacent" electrode therein, a sleeve of insulating materialextending from abutting relation with said adjacent electrode and spacedfrom the inner surface of said housing to provide therebetween a gasexpansion space, and clamp means at said one end of said housingabutting the adjacentend of said aaeasee sleeve and cooperating withsaid conductor rod to hold said sleeve in a predetermined position insaid housing.

13. In a circuit interrupting device,vin combination, a relatively longtubular housing, a

trode out of its end of said housing, a sleeve of insulating materialextending outwardly from abutting relation with each electrode andspaced from the inner surface of said housing to provide .therebetween agas expanison space, the outer end of each sleeve being spaced inwardlyfrom the adjacent end of said housing. and clamp means threadedinteriorly of each end of said housing including means abutting theadjacent end of the sleeve therein for holding the various parts inpositionin said. housing.

V CHARLES L. STROUP.

